The present invention relates to a vacuum switch suitable for a distribution and transformation system compatible between structural simplicity and reliability and a vacuum switchgear using the vacuum switch.
In regard to increasing demand of power consumption in a congested urban district, there are problems such as difficulty of obtaining a site for a distribution substation, lack of installation room for wire ducts, and requirement for a high operability of a supply facility. In order to solve these problems, it is necessary that the voltage is increased, that is, that load is actively absorbed in a voltage system having a large capacity per line. Increase in distribution voltage relates to forming of an effective electric power supply system. Therefore, it is necessary to make the distribution components and the distribution and transformation facility further compact.
As for the distribution and transformation components to be made compact, there is an SF6 gas insulation switchgear disclosed in, for example, Japanese Patent Application Laid-Open No.3-273804. The switchgear of the patent is formed in such as a breaker, two isolators and a grounding switch individually fabricated are contained in a unit chamber and a bus chamber of power distribution containers filled with an insulation gas.
Further, as a vacuum switchgear disclosed in Japanese Patent Application Laid-Open No.55-143727, there is a switchgear in which a movable electrode is horizontally rotated around a main axis to be brought in and off contact with a fixed electrode. As disclosed in Japanese Patent Application Laid-Open No.9-153320, there is a switchgear in which a movable conductor provided in a single vacuum container is moved on a close position, a open position, an isolation position and a grounding position while being rotated between a fixed conductor and a grounding conductor.
Further, as disclosed in the U.S. Pat. No. 3,814,882, Japanese Patent Application Laid-Open No.50-135563 and Japanese Patent Application Laid-Open No.58-145035, there is a switchgear in which a container formed of an insulating material is divided into two chambers, a movable electrode and a fixed electrode are individually disposed in the two chambers, and one of the chambers is evacuated to a vacuum and the other of the chambers is filled with an insulation gas such as SF6, or both of the chambers are evacuated to a vacuum. Furthermore, as disclosed in Japanese Patent Application Laid-Open No.48-81068, there is a switchgear in which a vacuum container is divided into three chambers.
The SF6 gas insulation switchgear disclosed in Japanese Patent Application Laid-Open No.3-273804, and the switchgear disclosed in the U.S. Pat. No. 3,814,882, Japanese Patent Application Laid-Open No.50-135563 use SF6 gas as the insulation medium. Use of SF6 gas is globally reduced because SF6 gas produces an ill effect on environment (from the viewpoint of prevention of global warming). Therefore, a switchgear not using SF6 gas is required.
The switchgear disclosed in Japanese Patent Application Laid-Open No.55-143727 needs sufficient safety measures in order to perform maintenance and inspection of the distribution and transformation system because the container is not grounded. That is, it is necessary that remaining charge and induced current are conducted to the ground by opening an isolator provided separately from a breaker and grounding a grounding switch after breaking the breaker. Further, since the components are individually disposed, there is a difficulty in making the switchgear small in size.
On the other hand, although the switchgear disclosed in Japanese Patent Application Laid-Open No.9-153320 is better in small size, there is a disadvantage in that all the functions are lost if a failure occurs because the close position, the open position, the isolation position and the grounding position are disposed in the single vacuum container.
Further, the switchgear disclosed in the U.S. Pat. No. 3,814,882, Japanese Patent Application Laid-Open No.50-135563 and Japanese Patent Application Laid-Open No.58-145035 can not be expected to made compact and can work only a single function because the container is made of an insulating material.
An object of the present invention is to provide a substantially small sized vacuum switch and a switchgear using the vacuum switch. Another object of the present invention is to provide a vacuum switch without using any insulation gas concerning the effect on environment and a switchgear using the vacuum switch. A further object of the present invention is to provide a vacuum switch which does not immediately lose the whole function and can maintain part of the function even if vacuum break occurs in a part of the vacuum switch, and to provide a vacuum switchgear using the vacuum switch. A still further object of the present invention is to provide a vacuum switch which can individually provide only a portion of a breaker, and only portions of a grounding switch and an isolator, and to provide a vacuum switchgear using the vacuum switch.
The present invention is characterized by that a grounded vacuum container is divided into a plurality of vacuum chambers through insulation bodies or a plurality of grounded vacuum containers are connected through insulation bodies, and a movable electrode disposed through an insulation body and driven by an operating mechanism and a fixed electrode disposed through an insulation body and paring with the movable electrode are gas-tightly sealed in each of the vacuum chambers or each of the vacuum containers.
A pair of the movable electrode and the fixed electrode compose the switching portion of any one of the breaker, the grounding switch or the isolator, and one or more of the switching portions may be arranged in one vacuum chamber or one vacuum container. The plurality of vacuum chambers or the plurality of vacuum containers are substantially arranged on a single axis and connected to each other through insulation bodies, and the electrode sealed inside the vacuum chamber or the vacuum container in an end portion in one side out of the plurality of vacuum chambers or the plurality of vacuum containers is electrically connected to a load side conductor, and the electrode sealed inside the vacuum chamber or the vacuum container in an end portion in the other side is electrically connected to a bus side conductor.
The electrical connection between the load side conductor and the electrode, or between the electrodes, or between the electrode and the bus side conductor, for example, the electrical connection between the rotationally moved switching portion of the breaker and the bus side conductor or between the switching portion of the grounding switch and the switching portion of the isolator is performed using a flexible conductor of a flexible member. A bellows may be used as the flexible member.
Therein, the switch means a machine for performing connecting and disconnecting between the fixed electrode and the movable electrode. The switchgear includes a control gear, and means a machine that one or more of the switching machine and one or more devices among an operating, a measuring, a protective and an adjusting devices and inner connections are combined, and these are contained in an enclosed box. Further, the switchgear includes an assembly of machines and devices comprising accessories and supporting structures in addition to the construction described above, and further includes a control unit for controlling the operating mechanism.
The breaker is a switchgear which is used for immediately isolating a position of occurrence of ground-fault or short-circuit in an electric power system from the system to prevent damage of a machine connected in series caused by a large current and to preventing damage of a failed machine by an arc. The isolator is a machine which performs switching of a charged electric path though it does not have breaking ability of a large current, and used for ensuring to isolate from a power supply when the circuit connection is changed or machines are maintained or inspected. There are various kinds of isolators for low voltage to high voltage. The grounding switch is a switching machine for ensuring safety by grounding conductors under a null-voltage condition during inspection and maintenance. The breaker can break all of charged current, normal current, abnormal current. The isolator can break charged current, but can not break both of normal current and abnormal current. The grounding switch can break none of charged current, normal current, abnormal current.
According to the present invention, the vacuum switch and the vacuum switchgear have effects that they are excellent in pollution control measures and they can attain small-sizing. The switchgear having a vacuum container divided into two or more chambers or two or more vacuum containers is highly reliable in the point that one of the chambers or the containers can maintain vacuum when vacuum of the other is broken. Further, since vacuum condition may be formed not only the whole system but also part of the system, for example, only breaker portion, a product type corresponding to a need and an economical product can be formed. Application of the flexible member to the electrical connection, for example, application of the flexible member to the electrical connection between the rotationally moved switching portion of the breaker and the bus side conductor can certainly perform the rotational moving and current conduction of the switching portion and contributes to compactness of the system. Application of the flexible member to the electrical connection between the switching portion of the grounding switch and the switching portion of the isolator contributes to certainty of current conduction and compactness of the system.